1. Field of the Invention
Fumigation has been an important means of controlling pests in agricultural commodities, and the process has generally been carried out using synthetic chemical pesticides and fumigants. The withdrawal of key chemicals from the market due to environmental and consumer safety concerns, however, has necessitated a search for effective alternatives to these substances. This invention relates to safe and effective replacements for current fumigation methods and compositions.
2. Description of the Prior Art
Methyl bromide is currently the most common fumigant used to control plant pests. The Montreal Protocol 1991 Assessment indicated that it was in a category of chemicals allegedly responsible for depleting the stratospheric ozone layer, the EPA indicated that action would be carried out under the Clean Air Act which calls for a phaseout of chemicals threatening the ozone layer by the year 2000. Annual losses to U.S. producers and consumers resulting from a ban of the agricultural uses of methyl bromide are estimated to be approximately $1.3 to $1.4 billion. According to industry sources, approximately 64 million pounds of methyl bromide were used in the United States in 1990, of which 5 million pounds were used for postharvest and quarantine treatments. Major crop losses are expected to be encountered in fresh market tomatoes, ornamentals, tobacco, peppers and strawberries if effective alternatives to methyl bromide are not found. A significant portion of the loss would be borne by U.S. consumers.
It has also been demonstrated that several naturally-occurring plant volatiles are effective for control of postharvest decay in a variety of agricultural commodities (Wilson et al., Plant Disease. 1987. vol. 71, pp. 316-319). However, in many cases it has been found that prolonged exposure of the commodities to these volatiles results in deleterious physiological changes in plant materials resulting in tissue deterioration (Stewart et al., Hort. Sci. 1980. vol. 15, pp. 148-149; Aharoni and Stadelbacher, Phytopathology. vol. 63, 544-545),manifesting itself as severe browning and development of water soaked areas. For this reason, these compounds have largely been unused for this purpose.
These events have thus provided an incentive for researchers to search for alternative fumigation and pest control means for the protection of postharvest agricultural commodities.